In xerography, or electrophotographic printing/copying, an electrophotographic imaging member is electrostatically charged. For optimal image production, the electrophotographic imaging member should be uniformly charged across its entire surface. The electrophotographic imaging member is then exposed to a light pattern of an input image to selectively discharge the surface of the electrophotographic imaging member in accordance with the image. The resulting pattern of charged and discharged areas on the electrophotographic imaging member forms an electrostatic charge pattern (i.e., a latent image) conforming to the input image. The latent image is developed by contacting it with finely divided electrostatically-attractable powder called toner. Toner is held on the image areas by electrostatic force. The toner image may then be transferred to a substrate or support member, and the image is then affixed to the substrate or support member by a fusing process to form a permanent image on the substrate or support member. After transfer, excess toner left on the electrophotographic imaging member is cleaned from its surface, and residual charge is erased from the electrophotographic imaging member.
Electrophotographic imaging members can be provided in a number of forms. For example, an electrophotographic imaging member can be a homogeneous layer of a single material, such as vitreous selenium, or it can be a composite layer containing an electrophotographic layer and another material. In addition, the electrophotographic imaging member can be layered.
Conventional layered electrophotographic imaging members generally have at least a flexible substrate support layer and two active layers. These active layers generally include a charge generation layer containing a light absorbing material, and a charge transport layer containing charge transport molecules. These layers can be in any order, and sometimes can be combined in a single or a mixed layer. The flexible substrate support layer can be formed of a conductive material. Alternatively, a conductive layer can be formed on top of a nonconductive flexible substrate support layer.
Conventional electrophotographic imaging members may be either a function-separation type photoreceptor, in which a layer containing a charge generation substance (charge generation layer) and a layer containing a charge transport substance (charge transport layer) are separately provided, or a monolayer type photoreceptor in which both the charge generation layer and the charge transport layer are contained in the same layer.
Conventional binders used in electrophotographic imaging members typically contain vinyl chloride. Examples of conventional binders are disclosed in U.S. Pat. No. 5,725,985, incorporated herein by reference in its entirety, and U.S. Pat. No. 6,017,666, incorporated herein by reference in its entirety. Additionally, electrophotographic imaging members may be non-halogenated polymeric binders, such as a non-halogenated copolymers of vinyl acetate and vinyl acid.
Conventional electrophotographic imaging members may have an undercoat layer interposed between the conductive support and the charge generation layer. Examples of conventional undercoat layers are disclosed in U.S. Pat. Nos. 4,265,990; 4,921,769; 5,958,638; 5,958,638; 6,132,912; 6,287,737; and 6,444,386; incorporated herein by reference in their entireties.